Learning by Accident

Excerpt from Crucible, September 2004.

««« Submitted by STAO Members in Region 3 and 4.

Learning by Accident is an ongoing Crucible feature, in which real-life lab accidents or incidents are recounted and explained. The goal is to highlight the consequence of ignoring safety rules so that science educators will be further encouraged to become knowledgeable, and to take appropriate action, in areas of safety that affect their daily activities in the science classroom. Submissions are encouraged. If requested, anonymity will be guaranteed. Please send written descriptions to Ian Mackellar, STAO Safety Committee Past-Chair, Box 191, MAITLAND, ON K0E 1P0

A Purple Problem: Safe Waste Disposal from School Science Laboratories

A school custodian, collecting waste materials to be taken to the local landfill site, started a fire when he added some broken glass from a ‘Broken Glass’ container to the regular garbage which contained paper towels and some unused potassium permanganate crystals from a recent student activity. The broken glass was from a flask which had originally contained glycerol.

Comments from the STAO Safety Committee
The spontaneous combustion of glycerol (flammable) in the presence of potassium permanganate (strong oxidizing agent) should not surprise most science teachers. Accordingly, this incident emphasizes the importance of rendering hazardouschemicals safe before leaving for disposal. Whenever possible, large pieces of broken laboratory glassware should be rinsed with a surfactant solution to remove traces of the contents before they are placed in the ‘Broken Glass’ container. Under no circumstances should oxidizing agents be placed in the regular waste container. Any excess permanganates from student experiments, as they contain a heavy metal, should be stored for disposal by a licensed contractor . (See STAO publication Stay Safe! for further guidance with respect disposal of hazardous waste).